These cylinder heads are designed for outstanding performance gains in 1962-79 389-455ci Pontiac engines. They are patterned after the 1969-70 Ram Air IV Pontiac cylinder head.
Performer heads #60579/60575 are 50-state emissions legal for 1965-79 vehicles. They have 87cc combustion chambers designed to maximize performance while using less expensive, low octane fuel with a streetable 9.5:1 compression ratio.
Performer RPM heads with 72cc combustion chamber are for higher compression engines. Performer RPM #60509 is semi-machined and must be finished by a professional head porter. They include valve guides and seats installed with no intake pushrod holes. Performer RPM #60587 is not port matched or bowl blended and is NHRA accepted for Stock and Super Stock.
Performer RPM CNC Heads feature the same specifications as the Performer RPM heads but have CNC-machined combustion chambers, which results in a consistent and precise chamber for improved flow.Features